Fluid storage and dispensing apparatus

ABSTRACT

A method of storing and dispensing a fluid includes providing a vessel configured for selective dispensing of the fluid therefrom. The vessel contains an ionic liquid therein. The fluid is contacted with the ionic liquid for take-up of the fluid by the ionic liquid. There is substantially no chemical change in the ionic liquid and the fluid. The fluid is released from the ionic liquid and dispensed from the vessel.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a division of co-pending application Ser. No.11/101,191, filed Apr. 7, 2005, entitled FLUID STORAGE AND PURIFICATIONMETHOD AND SYSTEM, the entire contents of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

Many industrial processes require a reliable source of process gases fora wide variety of applications. Often these gases are stored incylinders or vessels and then delivered to the process under controlledconditions from the cylinder. For example, the silicon semiconductormanufacturing industry, as well as the compound semiconductor industry,uses a number of hazardous specialty gases such as diborane, stibene,phosphine, arsine, boron trifluoride, hydrogen chloride, andtetrafluoromethane for doping, etching, thin-film deposition, andcleaning. These gases pose significant safety and environmentalchallenges due to their high toxicity and reactivity. Additionally,storage of hazardous gases under high pressure in metal cylinders isoften unacceptable because of the possibility of developing a leak orcatastrophic rupture of the cylinder, cylinder valve, or downstreamcomponent.

In order to mitigate some of these safety issues associated with highpressure cylinders, there is a need for a low pressure storage anddelivery system. Additionally, some gases, such as diborane, tend todecompose when stored for a period of time. Thus, it would be useful tohave a way to store unstable gases in a manner that reduces oreliminates the decomposition.

It is also desirable to have a method of removing impurities from gases,particularly in the semiconductor industry. The growth of high qualitythin film electronic and optoelectronic cells by chemical vapordeposition or other vapor-based techniques is inhibited by a variety oflow-level process impurities which are present in gas streams involvedin semiconductor manufacturing or are contributed from variouscomponents such as piping, valves, mass flow controllers, filters, andsimilar components. These impurities can cause defects that reduceyields by increasing the number of rejects, which can be very expensive.

Chemical impurities may originate in the production of the source gasitself, as well as in its subsequent packaging, shipment, storage,handling, and gas distribution system. Although source gas manufacturerstypically provide analyses of source gas materials delivered to thesemiconductor manufacturing facility, the purity of the gases may changebecause of leakage into or outgassing of the containers, e.g. gascylinders, in which the gases are packaged. Impurity contamination mayalso result from improper gas cylinder changes, leaks into downstreamprocessing equipment, or outgassing of such downstream equipment. Sourcegases may include impurities, or impurities may occur as a result ofdecomposition of the stored gases. Furthermore, the impurity levelswithin the gas container may increase with length of storage time andcan also change as the container is consumed by the end user. Thus,there remains a need to be able to remove contaminants from gases,particularly to very low levels.

BRIEF SUMMARY

In one aspect of the invention, a method of storing and dispensing afluid is provided. The method includes providing a vessel configured forselective dispensing of the fluid therefrom. The vessel contains anionic liquid therein. The fluid is contacted with the ionic liquid fortake-up of the fluid by the ionic liquid. There is substantially nochemical change in the ionic liquid and the fluid. The fluid is releasedfrom the ionic liquid and dispensed from the vessel. The fluid may beselected from alcohols, aldehydes, amines, ammonia, aromatichydrocarbons, arsenic pentafluoride, arsine, boron trichloride, borontrifluoride, carbon disulfide, carbon monoxide, carbon sulfide,diborane, dichlorosilane, digermane, dimethyl disulfide, dimethylsulfide, disilane, ethers, ethylene oxide, fluorine, germane, germaniummethoxide, germanium tetrafluoride, hafnium methylethylamide, hafniumt-butoxide, halogenated hydrocarbons, halogens, hexane, hydrogen,hydrogen cyanide, hydrogen halogenides, hydrogen selenide, hydrogensulfide, ketones, mercaptans, nitric oxides, nitrogen, nitrogentrifluoride, organometallics, oxygenated-halogenated hydrocarbons,phosgene, phosphorus trifluoride, n-silane, pentakisdimethylaminotantalum, silicon tetrachloride, silicon tetrafluoride, stibine,styrene, sulfur dioxide, sulfur hexafluoride, sulfur tetrafluoride,tetramethyl cyclotetrasiloxane, titanium diethylamide, titaniumdimethylamide, trichlorosilane, trimethyl silane, tungsten hexafluoride,and mixtures thereof. The ionic liquid may be selected frommono-substituted imidazolium salts, di-substituted imidazolium salts,tri-substituted imidazolium salts, pyridinium salts, phosphonium salts,ammonium salts, tetralkylammonium salts, guanidinium salts, isouroniumsalts, and mixtures thereof.

In another aspect of the invention, a method of separating an impurityfrom a fluid mixture is provided. The fluid mixture includes a fluid andthe impurity. A device contains an ionic liquid and is configured forcontacting the ionic liquid with the fluid mixture. The fluid mixture isintroduced into the device. The fluid mixture is contacted with theionic liquid. A portion of the impurity is retained within the ionicliquid to produce a purified fluid.

In another aspect of the invention, a method of storing and stabilizingan unstable fluid is provided. The method includes providing a vesselcontaining an ionic liquid therein. The unstable fluid is contacted withthe ionic liquid for take-up of the unstable fluid by the ionic liquid.The unstable fluid is then stored within the ionic liquid for a periodof time, during which period of time there is substantially nodecomposition of the unstable fluid. The unstable fluid may be selectedfrom digermane, disilane, hydrogen selenide, borane, diborane, stibene,nitric oxide, organometallics, and halogenated oxy-hydrocarbons.

The foregoing paragraphs have been provided by way of generalintroduction, and are not intended to limit the scope of the followingclaims. The presently preferred embodiments, together with furtheradvantages, will be best understood by reference to the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of a vessel for storing a fluid in an ionicliquid.

FIG. 2 shows another embodiment of a device for storing a fluid in anionic liquid.

FIG. 3 shows an embodiment of a device for purifying a fluid with anionic liquid.

FIG. 4 shows another embodiment of a device for purifying a fluid withan ionic liquid.

DETAILED DESCRIPTION

The invention is described with reference to the drawings. Therelationship and functioning of the various elements of this inventionare better understood by the following detailed description. However,the embodiments of this invention as described below are by way ofexample only, and the invention is not limited to the embodimentsillustrated in the drawings.

The present invention is directed to the use of ionic liquids to store afluid material such as a gas or liquid. A vessel is configured for theselective dispensing of the fluid and contains an ionic liquid. Thefluid is contacted with the ionic liquid for take-up of the fluid by theionic liquid. This allows storage of the fluid for a period of time. Inone embodiment, the material in the storage vessel is at high pressure,for example up to about 4000 psi, preferably up to at least about 2000psi. In another embodiment, the pressure of the material in the storagevessel is at around atmospheric pressure, which allows for safer storageconditions compared to high-pressure storage vessels.

The ionic liquids may also be used to store unstable fluids such asdiborane which tend to decompose. The storage in the ionic liquid canreduce or eliminate the decomposition of the unstable fluids.

The present invention is also directed to the use of ionic liquids toremove impurities from a fluid mixture. A device contains an ionicliquid and is configured for contacting the ionic liquid with the fluidmixture. The fluid mixture is introduced into the device and the fluidmixture is contacted with the ionic liquid. A portion of the impuritiesare retained within the ionic liquid to produce a purified fluid. Thispurification method may be combined with the previously describedstorage method.

Ionic liquids are a relatively new class of materials which can offersuch physical properties as extremely low vapor pressure, high thermalstability, and low viscosity. Generally, ionic liquids consist of abulky, asymmetric cation and an inorganic anion. The bulky, asymmetricnature of the cation prevents tight packing, which decreases the meltingpoint. Due to the wide variety of cations and anions possible for suchion pairs, a wide range of gas solubilities is conceivable, for avariety of inorganic and organic materials. The physical properties ofionic liquids can include good dissolution properties for most organicand inorganic compounds; high thermal stability; non-flammability;negligible vapor pressure; low viscosity, compared to other ionicmaterials; and recyclability.

The wide range of chemical functionalities available with ionic liquidsoffers possibilities for gas delivery and control. For example, ionicliquids may provide the capability to control the release of a gasand/or its impurities via solubility control with temperature orpressure. This may enable the storage of a gas and its impurities, whileselectively releasing only the desired gas by changing certainparameters, such as temperature or pressure, leaving the impuritiesbehind. Thus there is potential for an ionic liquid system that couldfunction as a 2-in-1 system, providing both storage and purification inone container.

Ionic liquids can have a stabilizing effect on intermediate reactionspecies in organic synthesis and catalysis. Thus, ionic liquids canoffer stabilizing effects for unstable gas molecules. Thus, utilizationwith even a small amount of ionic liquid, can reduce or eliminate thedecomposition of the unstable fluids. Storage of a gas or other fluid inan ionic liquid may also be combined with the previously mentionedpurification system to provide a 3-in-1 storage, stabilization, andpurification system.

One potential issue in the use of ionic liquids for the storage of gasesis the vapor pressure of the ionic liquids. The vapor pressure of theionic liquid can contaminate the delivered gas with ionic liquid. Thepresent understanding is that ionic liquids have very low or possibly nomeasurable vapor pressure of their own. This quality is an attractivefeature of ionic liquids for use with storage and purification of gases.Vapor pressures have been reported for mixtures of ionic liquids withother dissolved liquids. The vapor pressure of the ionic liquids used inthe present invention are preferably less than about 10⁻⁴ Torr at 25°C., more preferably less than about 10⁻⁶ Torr at 25° C.

The mechanism for the dissolution of a fluid within an ionic liquid isbelieved to be due to intermolecular forces. While not intending to bebound by any particular theory, possible factors that influence thesolubility include hydrogen bonding, dielectric constant, dipole moment(polarizability), high pi interaction, length of carbon chain, number ofcarbon double bonds, the purity of the ionic liquid, chirality, andsteric hindrance. It is not believed that the fluids chemically reactwith the ionic liquid; rather, it is believed that the fluids simplydissolve in the ionic liquid without the breaking of bonds. The breakingof bonds in either the ionic liquid or the fluids being stored thereinwould change the chemical and physical properties of the ionic liquid orfluids and could cause the new species to be considered a new impurity.It is the intention of this invention to store the fluid of interest inan ionic liquid wherein the fluid molecules remains intact and areremoved from the ionic liquid with the same molecular structure as theywere introduced into the ionic liquid.

The solubility of a gas in an ionic liquid varies with physicalparameters such as temperature and pressure. However, it is also evidentthat the gas solubilities obtained depends on the ionic liquid used,particularly the anion and cation used. While not intending to be boundby any particular theory, the current understanding is that the anionhas a strong influence on gas solubility. Specifically, the moreinteraction between the anion, the more dissolution appears to occur.The cation seems to be of secondary influence. Thus, several propertiesof the anion, the cation, and the dissolved gas play a role in theseinteractions. In addition, mixtures of different ionic liquids couldresult in unexpected high solubilities of various fluids.

The purity of an ionic liquid is also believed to have an impact ontheir behavior. Ionic liquids which have been dried or baked, thusleaving them substantially anhydrous, may exhibit greater increasedcapacity for taking up fluid components. In addition, the presence ofwater or other impurities may decrease the solubility of certain fluidcomponents, especially those gas components that are hydrophobic.

The method of storing and dispensing a fluid includes providing avessel. On embodiment of a vessel 10 is shown in FIG. 1. The vessel 10includes a fluid inlet 20, an ionic liquid inlet 30, and a fluid outlet32. The fluid inlet 20 is connected to a fluid source 14 which iscontrolled by a valve 18. The ionic liquid inlet 30 is connected to anionic liquid source 12 which is controlled by a valve 16. The fluidoutlet 32 is controlled by valve 26. The vessel is configured forselective dispensing of the fluid therefrom. The vessel is charged withan ionic liquid 22 through inlet 30. A vacuum bake procedure may beconducted on the vessel 10 to remove contaminants or other impuritiesfrom the ionic liquid, preferably by pulling a vacuum while heating.This is done in order to remove any trace moisture and/or other volatileimpurities from the ionic liquid and the fluid distribution components.The ionic liquid is allowed to cool to the desired operatingtemperature.

The source fluid is then introduced into the vessel 10 until the take-upor dissolution of the fluid by the ionic liquid is complete. The fluidmay be a gas or a liquid such as a liquefied gas. The fluid is contactedwith the ionic liquid for take-up of the fluid by the ionic liquid.There is substantially no chemical change in the ionic liquid and thefluid. By “substantially no chemical change” is meant that nosubstantial amount of bonds in the fluid and the ionic liquid are beingbroken, such that the fluid and the ionic liquid retain their chemicalidentity. It is undesirable for the fluid to react with the ionic liquidto any significant effect. A reaction between the fluid and the ionicliquid would be expected to generate impurities or consume the fluid ofinterest.

The fluid may be introduced at any suitable pressure. In one embodiment,the fluid is a gas at a temperature of about 5 psi. In anotherembodiment, the gas is introduced at a pressure of at least about 100psi, preferably up to about 2000 psi. The gas is introduced until theinlet and outlet concentrations are equivalent, indicating the ionicliquid is saturated and cannot accept any further gas under the existingconditions. At this time, the source gas flow is stopped.

In one embodiment, contacting the fluid with the ionic liquid comprisesbubbling the fluid mixture through the ionic liquid, as shown in FIG. 1.The vessel 10 is charged with a fluid through inlet 28 and through diptube 20, from whence it bubbles through ionic liquid 22.

In another embodiment, the fluid is first introduced and then the vesselis mechanically agitated in order to contact the fluid with the ionicliquid. FIG. 2 shows an embodiment of a vessel 80 for storing a fluid inan ionic liquid. The ionic liquid 22 is put into the vessel before valveassembly 82 is inserted unto the vessel 80. The fluid is then added tothe vessel 80 containing the ionic liquid in the conventional fashionthrough inlet port 84 in valve assembly 82. The vessel 80 would then bemechanically agitated to contact the fluid with the ionic liquid 22. Thefluid may be removed through outlet port 86.

In one embodiment, the fluid is a liquid. The vessel 80 shown in FIG. 2may also be used to store a liquid in the ionic liquid. The ionic liquid22 is put into the vessel before valve assembly 82 is inserted into thevessel 80. The liquid is then added to the vessel 80 in the conventionalfashion through inlet port 84 in valve assembly 82. The vessel 80 wouldthen be mechanically agitated to contact the liquid with the ionicliquid 22. The liquid may be removed through outlet port 86.

In another embodiment, countercurrent flow of the ionic liquid and thefluid is used to contact the fluid with the ionic liquid. In anotherembodiment, the fluid is a liquid, and the liquid and the ionic liquidare mixed to contact the fluid with the ionic liquid.

The fluid stored within the ionic liquid may be removed from the ionicliquid by any suitable method. The fluid is released from the ionicliquid in a substantially unreacted state. Pressure-mediated andthermally-mediated methods and sparging, alone or in combination, arepreferred. In pressure-mediated evolution, a pressure gradient isestablished to cause the gas to evolve from the ionic liquid. In oneembodiment, the pressure gradient is in the range of about atmosphericpressure to about 4000 psig. In a more preferred embodiment, thepressure gradient is typically in the range from 10⁻⁷ to 600 Torr at 25°C. For example, the pressure gradient may be established between theionic liquid in the vessel, and the exterior environment of the vessel,causing the fluid to flow from the vessel to the exterior environment.The pressure conditions may involve the imposition on the ionic liquidof vacuum or suction conditions which effect extraction of the gas fromthe vessel.

In thermally-mediated evolution, the ionic liquid is heated to cause theevolution of the gas from the ionic liquid so that the gas can bewithdrawn or discharged from the vessel. Typically, the temperature ofthe ionic liquid for thermal-mediated evolution ranges from −50° C. to200° C., more preferably from 30° C. to 150° C. In one embodiment, thevessel containing the fluid and the ionic liquid is transported warm(i.e., around room temperature), then cooled when it is stored or usedat the end user's site. In this manner, the fluid vapor pressure can bereduced at the end user's site and therefore reduce the risk of releaseof the gas from the vessel. Once the vessel is secured in a suitablelocation, the vessel can be chilled and the temperature can becontrolled in such a manner as to limit the amount of gas pressure thatis present in the container and piping. As the contents of the cylinderor other gas storage device are consumed, the temperature of thecylinder can be elevated to liberate the gas from the ionic liquid andto maintain the necessary amount of gas levels in the cylinder andpiping.

The vessel may also be sparged with a secondary gas, in order to deliverthe stored primary gas. In sparging, a secondary gas is introduced intothe vessel in order to force the primary gas out of the ionic liquid andout of the storage container. Sparging of a container can take placewherein the secondary gas is selected from a group of gases that hasrelatively low solubility in the ionic liquid. The secondary gas isintroduced into the ionic liquid in a manner wherein the secondary gasbubbles through the ionic liquid and displaces the primary gas from theionic liquid. The resultant gas mixture of primary gas and secondary gasthen exit the gas storage container and are delivered to a downstreamcomponent in the gas distribution system. The sparging parameters shouldbe selected such that the maximum amount of primary gas is removed fromthe ionic liquid. This includes selection of the appropriate geometry ofthe sparging vessel such that the secondary gas has an enhanced pathwayfor the interaction or contact between the secondary fluid and the ionicliquid. In practice, this could be use of a long and narrow storagecontainer wherein the secondary fluid is introduced at the bottom of thecontainer and the outlet of the container is near the top. Additionally,a device such as a diffuser can be used within the storage containerthat causes the bubbles of the secondary gas to be very small andnumerous. In this manner, the surface area or contact area of thebubbles of the secondary gas is enhanced with the ionic liquid. Finally,the parameters of temperature and pressure within the sparging storagecontainer can be adjusted such that the desired concentration of thesecondary gas and primary gas are constant and fall within a desiredrange. In this example, the sparging vessel can be a separate containerfrom the typical storage container such as a gas cylinder, or thetypical storage container can be used as the sparging vessel dependingon the requirements of the specific application.

When released from the ionic liquid, the gas flows out of the vessel, bysuitable means such as a discharge port or opening 24 in FIG. 1. A flowcontrol valve 26 may be joined in fluid communication with the interiorvolume of the vessel. A pipe, conduit, hose, channel or other suitabledevice or assembly by which the fluid can be flowed out of the vesselmay be connected to the vessel.

The present invention also provides a fluid storage and dispensingsystem. The system includes a fluid storage and dispensing vesselconfigured to selectively dispense a fluid therefrom. A suitable vesselis, for example, a container that can hold up to 1000 liters. A typicalvessel size is about 44 liters. The vessel should be able to containfluids at a pressure of up to about 2000 psi, preferably up to about4000 psi. However, the vessel may also operate at around atmosphericpressure. Preferably, the container is made of carbon steel, stainlesssteel, nickel or aluminum. In some cases the vessel may contain interiorcoatings in the form of inorganic coatings such as silicon and carbon,metallic coatings such as nickel, organic coatings such as paralyene orTeflon based materials. The vessel contains an ionic liquid whichreversibly takes up the fluid when contacted therewith. The fluid isreleasable from the ionic liquid under dispensing conditions.

A variety of ionic liquids can be used in the present invention.Additionally, two or more ionic liquids may be combined for use in anyof the aspects of the present invention. In one embodiment, the ionicliquid is selected from mono-substituted imidazolium salts,di-substituted imidazolium salts, tri-substituted imidazolium salts,pyridinium salts, pyrrolidinium salts, phosphonium salts, ammoniumsalts, tetralkylammonium salts, guanidinium salts, isouronium salts, andmixtures thereof. In this context, the listed salts include any compoundthat contains the listed cation. In another embodiment, the ionic liquidis selected from a subset of the previous list and includes phosphoniumsalts, ammonium salts, tetralkylammonium salts, guanidinium salts,isouronium salts, and mixtures thereof. In one embodiment, the ionicliquid includes a cation component selected from mono-substitutedimidazoliums, di-substituted imidazoliums, tri-substituted imidazoliums,pyridiniums, pyrrolidiniums, phosphoniums, ammoniums,tetralkylammoniums, guanidiniums, and uroniums; and an anion componentselected from acetate, cyanates, decanoates, halogenides, sulfates,sulfonates, amides, imides, methanes, borates, phosphates, antimonates,tetrachoroaluminate, thiocyanate, tosylate, carboxylate,cobalt-tetracarbonyl, trifluoroacetate andtris(trifluoromethylsulfonyl)methide. Halogenide anions includechloride, bromide, iodide. Sulfates and sulfonate anions include methylsulfate, ethyl sulfate, butyl sulfate, hexyl sulfate, octyl sulfate,hydrogen sulfate, methane sulfonate, dodecylbenzene sulfonate,dimethyleneglycolmonomethylether sulfate, trifluoromethane sulfonate.Amides, imides, and methane anions include dicyanamide,bis(pentafluoroethylsulfonyl)imide, bis(trifluoromethylsulfonyl)imide,bis(trifluoromethyl)imide. Borate anions include tetrafluoroborate,tetracyanoborate, bis[oxalato(2-)]borate,bis[1,2-benzenediolato(2-)-O,O′]borate, bis[salicylato(2-)]borate.Phosphate and phosphinate anions include hexafluorophosphate,diethylphosphate, bis(pentafluoroethyl)phosphinate,tris(pentafluoroethyl)trifluorophosphate,tris(nonafluorobutyl)trifluorophosphate. Anitmonate anions includehexafluoroantimonate. Other anions include tetrachoroaluminate, acetate,thiocyanate, tosylate, carboxylate, cobalt-tetracarbonyl,trifluoroacetate and tris(trifluoromethylsulfonyl)methide. Various ionicliquids are available from BASF, Merck, Strem Chemicals, and Aldrich.

Preferred ionic liquids used in the present invention may be dividedinto the following categories: standard, acidic, acidic water reactive,and basic. Standard ionic liquids include but are not limited to1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazoliummethanesulfonate, 1-butyl-3-methylimidazolium chloride,1-butyl-3-methylimidazolium methanesulfonate, methyl-tri-n-butylammoniummethylsulfate, 1-ethyl-2,3-dimethylimidazolium ethylsulfate,1,2,3-trimethylimidazolium methylsulfate. Acidic ionic liquids includemethylimidazolium chloride, methylimidazolium hydrogensulfate,1-ethyl-3-methylimidazolium hydrogensulfate, 1-butyl-3-methylimidazoliumhydrogensulfate. Acidic water reactive liquids include1-ethyl-3-methylimidazolium tetrachloroaluminate and1-butyl-3-methylimidazolium tetrachloroaluminate. Basic ionic liquidsinclude 1-ethyl-3-methylimidazolium acetate and1-butyl-3-methylimidazolium acetate.

Another way the preferred ionic liquids in the present invention may becategorized is by functional group of the cation. This includes but isnot limited to the following categories: mono-substituted imidazoliums,di-substituted imidazoliums, tri-substituted imidazoliums, pyridiniums,pyrrolidiniums, phosphoniums, ammoniums, tetralkylammoniums,guanidiniums, and uroniums. Mono-substituted imidazolium ionic liquidsinclude 1-methylimidazolium tosylate, 1-methylimidazoliumtetrafluoroborate, 1-methylimidazolium hexafluorophosphate,1-methylimidazolium tifluoromethanesulfonate, 1-butylimidazoliumtosylate, 1-butylimidazolium tetrafluoroborate, 1-methylimidazoliumhexafluorophosphate, 1-methylimidazolium tifluoromethanesulfonate.

Di-substituted imidazolium ionic liquids include1,3-dimethylimidiazolium methylsulfate, 1,3-dimethylimidiazoliumtrifluoromethanesulfonate, 1,3-dimethylimidiazoliumbis(pentafluoroethyl)phosphinate, 1-ethyl-3-methylimidiazoliumthiocyanate, 1-ethyl-3-methylimidiazolium dicyanamide,1-ethyl-3-methylimidiazolium cobalt-tetracarbonyl,1-propyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazoliumhexafluoroantimonate, 1-octadecyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide, 1-benzyl-3-methylimidazolium bromide,1-phenylpropyl-3-methylimidazolium chloride.

Tri-substituted imidazolium ionic liquids include1-ethyl-2,3-dimethylimidazolium chloride,1-butyl-2,3-dimethylimidazolium octylsulfate,1-propyl-2,3-dimethylimidazolium chloride,1-hexyl-2,3-dimethylimidazolium tetrafluoroborate,1-hexadecyl-2,3-dimethylimidazolium iodide. Pyridinium ionic liquidsinclude n-ethylpyridinium chloride, n-butylpyridinium bromide,n-hexylpyridinium n-octylpyridinium chloride, 3-methyl-n-butylpyridiniummethylsulfate, 3-ethyl-n-butylpyridinium hexafluorophosphate,4-methyl-n-butylpyridinium bromide, 3,4-dimethyl-n-butylpyridiniumchloride, 3,5-dimethyl-n-butylpyridinium chloride.

Pyrrolidinium ionic liquids include 1,1-dimethylpyrrolidiniumtris(pentafluoroethyl)trifluorophosphate, 1-ethyl-1-methylpyrrolidiniumdicyanamide, 1,1-dipropylpyrrolidiniumbis(trifluoromethylsulfonyl)imide, 1-butyl-1-methylpyrrolidiniumbromide, 1-butyl-1-ethylpyrrolidinium bromide,1-octyl-1-methylpyrrolidinium dicyanamide.

Phosphonium ionic liquids include tetraoctylphosphonium bromide,tetrabutylphosphonium bis[oxalato(2-)]-borate,trihexyl(tetradecyl)phosphonium dicyanamide, benzyltriphenylphosphoniumbis(trifluoromethyl)imide, tri-iso-butyl(methyl)phosphonium tosylate,ethyl(tributyl)phosphonium diethylphosphate,tributyl(hexadecyl)phosphonium chloride.

Ammonium ionic liquids include tetramethylammoniumbis(trifluoromethylsulfonyl)imide, tetraethylammoniumbis-[salicylato-(2-)]-borate, tetrabutylammonium tetracyanoborate,methyltrioctylammonium trifluoroacetat.

Guanidinium ionic liquids includeN,N,N′,N′,N″-pentamethyl-N″-isopropylguanidiniumtris(pentafluoroethyl)trifluorophosphate,N,N,N′,N′,N″-pentamethyl-N″-isopropylguanidiniumtris(pentafluoroethyl)trifluoromethanesulfonate, hexamethylguanidiniumtrs(pentafluoroethyl)trifluorophosphate, hexamethylguanidiniumtrifluoromethanesulfonate.

Uronium ionic liquids include S-methyl-N,N,N′,N′-tetramethylisouroniumtrifluoromethanesulfonate, O-methyl-N,N,N′,N′-tetramethylisouroniumtris(pentafluoroethyl)trifluorophosphate, O-ethyl-N,N,N′,N′-tetramethylisouronium tris(pentafluoroethyl)trifluorophosphate,S-ethyl-N,N,N′, N′-tetramethylisouronium trifluoromethanesulfonate,S-ethyl-N,N,N′, N′-tetramethylisothiouronium trifluoromethanesulfonate.

In one embodiment, the ionic liquid used to store a fluid does notinclude imidazolium compounds. In another embodiment, the ionic liquidused to store a fluid does not include a nitrogen-containingheterocyclic cation.

The fluids which may be stored, purified, or stabilized in the ionicliquids include, but are not limited to, alcohols, aldehydes, amines,ammonia, aromatic hydrocarbons, arsenic pentafluoride, arsine, borontrichloride, boron trifluoride, carbon dioxide, carbon disulfide, carbonmonoxide, carbon sulfide, chlorine, diborane, dichlorosilane, digermane,dimethyl disulfide, dimethyl sulfide, disilane, ethane, ethers, ethyleneoxide, fluorine, germane, germanium methoxide, germanium tetrafluoride,hafnium methylethylamide, hafnium t-butoxide, halogenated hydrocarbons,halogens, hexane, hydrogen, hydrogen cyanide, hydrogen halogenides,hydrogen selenide, hydrogen sulfide, ketones, mercaptans, methane,nitric oxides, nitrogen, nitrogen trifluoride, noble gases,organometallics, oxygen, oxygenated-halogenated hydrocarbons, phosgene,phosphine, phosphorus trifluoride, n-silane, pentakisdimethylaminotantalum, propane, silicon tetrachloride, silicon tetrafluoride,stibine, styrene, sulfur dioxide, sulfur hexafluoride, sulfurtetrafluoride, tetramethyl cyclotetrasiloxane, titanium diethylamide,titanium dimethylamide, trichlorosilane, trimethyl silane, tungstenhexafluoride, water, and mixtures thereof.

In another embodiment, the fluids which may be stored, purified, orstabilized in the ionic liquids includes a subset of the previous listedfluids and include alcohols, aldehydes, amines, ammonia, aromatichydrocarbons, arsenic pentafluoride, arsine, boron trichloride, borontrifluoride, carbon disulfide, carbon monoxide, carbon sulfide,chlorine, diborane, dichlorosilane, digermane, dimethyl disulfide,dimethyl sulfide, disilane, ethers, ethylene oxide, fluorine, germane,germanium methoxide, germanium tetrafluoride, hafnium methylethylamide,hafnium t-butoxide, halogenated hydrocarbons, halogens, hexane,hydrogen, hydrogen cyanide, hydrogen halogenides, hydrogen selenide,hydrogen sulfide, ketones, mercaptans, nitric oxides, nitrogen, nitrogentrifluoride, organometallics, oxygenated-halogenated hydrocarbons,phosgene, phosphine, phosphorus trifluoride, n-silane,pentakisdimethylamino tantalum, silicon tetrachloride, silicontetrafluoride, stibine, styrene, sulfur dioxide, sulfur hexafluoride,sulfur tetrafluoride, tetramethyl cyclotetrasiloxane, titaniumdiethylamide, titanium dimethylamide, trichlorosilane, trimethyl silane,tungsten hexafluoride, and mixtures thereof.

By way of illustration, examples of some of these classes of fluids willnow be listed. However, scope of the invention is not limited to thefollowing examples. Alcohols include ethanol, isopropanol, and methanol.Aldehydes include acetaldehyde. Amines include dimethylamine andmonomethylamine. Aromatic compounds include benzene, toluene, andxylene. Ethers include dimethyl ether, and vinyl methyl ether. Halogensinclude chlorine, fluorine, and bromine. Halogenated hydrocarbonsinclude dichlorodifluoromethane, tetrafluoromethane,clorodifluoromethane, trifluoromethane, difluoromethane, methylfluoride, 1,2-dichlorotetrafluoroethane, hexafluoroethane,pentafluoroethane, halocarbon 134a tetrafluoroethane, difluoroethane,perfluoropropane, octafluorocyclobutane, chlorotrifluoroethylene,hexafluoropropylene, octafluorocyclopentane, perfluoropropane,1,1,1-trichloroethane, 1,1,2-trichloroethane, methyl chloride, andmethyl fluoride. Ketones include acetone. Mercaptans include ethylmercaptan, methyl mercaptan, propyl mercaptan, and n,s,t-butylmercaptan. Nitrogen oxides include nitrogen oxide, nitrogen dioxide, andnitrous oxide. Organometallics include trimethylaluminum,triethylaluminum, dimethylethylamine alane, trimethylamine alane,dimethylaluminum hydride, tritertiarybutylaluminum,Tritertiarybutylaluminum trimethylindium (TMI), trimethylgallium (TMG),triethylgallium (TEG), dimethylzinc (DMZ), diethylzinc (DEZ),carbontetrabromide (CBr₄), diethyltellurium (DETe) and magnesocene(Cp₂Mg). Oxygenated-halogenated-hydrocarbons includeperfluoroethylmethylether, perfluoromethylpropylether,perfluorodimethoxymethane, and hexafluoropropylene oxide. Other fluidsinclude vinyl acetylene, acrylonitrile, and vinyl chloride.

Other fluids which may be stored, purified, or stabilized in ionicliquids include materials used for thin film deposition applications.Such materials include, but are not limited to, tetramethylcyclotetrasiloxane (TOMCTS), titanium dimethylamide (TDMAT), titaniumdiethylamide (TDEAT), hafnium t-butoxide (Hf(OtBu)4), germaniummethoxide(Ge(OMe)4), pentakisdimethylamino tantalum (PDMAT) hafniummethylethylamide (TEMAH) and mixtures thereof.

The fluids which may be stored in the ionic liquids may be divided intocategories including include stable gases, stable liquefied gases,unstable gases, and unstable liquefied gases. The term stable isrelative and includes gases which do not substantially decompose overthe shelf life of a storage vessel at the typical temperatures andpressures at which those skilled in the art would store the gases.Unstable refers to materials which are prone to decomposition undertypical storage conditions and thus are difficult to store.

Stable gases include include nitrogen, argon, helium, neon, xenon,krypton; hydrocarbons include methane, ethane, and propanes; hydridesinclude silane, disilane, arsine, phosphine, germane, ammonia;corrosives include hydrogen halogenides such as hydrogen chloride,hydrogen bromide, and hydrogen fluoride, as well as chlorine,dichlorosilane, trichlorosilane, carbon tetrachloride, borontrichloride, tungsten hexafluoride, and boron trifluoride; oxygenatesinclude oxygen, carbon dioxide, nitrous oxide, and carbon monoxide; andother gases such as hydrogen, deuterium, dimethyl ether, sulfurhexafluoride, arsenic pentafluoride, and silicon tetrafluoride.

Stable liquefied gases include inerts such as nitrogen and argon;hydrocarbons such as propane; hydrides such as silane, disilane, arsine,phosphine, germane, and ammonia; fluorinates such as hexafluoroethane,perfluoropropane, and perfluorobutane; corrosives such as hydrogenchloride, hydrogen bromide, hydrogen fluoride, chlorine, dichlorosilane,trichlorosilane, carbon tetrachloride, boron trichloride, borontrifluoride, tungsten hexafluoride, and chlorine trifluoride; andoxygenates such as oxygen and nitrous oxide.

Unstable gases include digermane, borane, diborane, stibene, disilane,hydrogen selenide, nitric oxide, fluorine and organometallics includingalanes, trimethyl aluminum and other similar gases. These unstable gasesmay also be liquefied.

In one embodiment, a fluid such as fluorine could be stored with fullyfluorinated ionic liquid such as perfluorinated ammoniumhexafluorophosphate.

The present invention also provides a method of separating an impurityfrom a fluid mixture. In this instance, the fluid mixture includes afluid and the impurity. FIG. 3 shows an embodiment of a device 40 forpurifying a fluid with an ionic liquid. A device containing the ionicliquid is configured for contacting the ionic liquid with the fluidmixture. A source 46 for the fluid mixture is controlled by valve 48.The fluid mixture is introduced through inlet 50 into the device 40 andcontacted with the ionic liquid. The ionic liquid is introduced throughinlet 52 from ionic liquid source 42 by valve 44. A portion of theimpurities is retained within the ionic liquid to produce a purifiedfluid. The purified fluid is released from the device through outlet 54,which is controlled by valve 56.

FIG. 4 shows another embodiment of a device 40 for purifying a fluidwith an ionic liquid. Contacting the fluid with the ionic liquidcomprises bubbling the fluid mixture through the ionic liquid. Thevessel 60 includes a valve assembly 62, an ionic liquid inlet 64, afluid inlet 66, and a dip tube 78. The valve assembly 62 includes anionic liquid inlet valve 68 and a fluid inlet valve 70. The vessel 60 ischarged with an ionic liquid 22 through inlet 64. The vessel 60 ischarged with a fluid through inlet 66 and through dip tube 78, fromwhence it bubbles through ionic liquid 22.

Alternatively, as will be described below, the impurity may retained ona solid material that has been introduced into the ionic liquid. Inaddition, mixtures of one or more ionic liquids can be used with orwithout the additional solid phase purification material to adjust thesolubility of the fluid as well as the purifying ability of the ionicliquid. Additionally, non-ionic liquids can be mixed with the ionicliquids to either capture impurities present in the fluid or tosubstantially modify the impurities into a form that is retained by thepurifying liquid or ionic liquid. The net effect is that the impuritiesare separated from the fluid and the purified fluid is then releasedfrom the device.

It is understood that the fluid and fluid mixture may include liquids,vapors (volatilized liquids), gaseous compounds, and/or gaseouselements. Furthermore, while reference is made to “purified,” it isunderstood that purified may include purification to be essentially freeof one or more impurities, or simply lowering the lower level ofimpurities in the fluid mixture. Impurities include any substance thatmay be desirable to have removed from the fluid mixture, or areundesirable within the fluid mixture. Impurities included can bevariants or analogs of the fluid itself if they are undesirable.Impurities that would typically be desired to be removed include but arenot limited to water, CO₂, oxygen, CO, NO, NO₂ N₂O₄, SO₂, SO₃, SO, S₂O₂,SO₄, and mixtures thereof. Additionally, impurities include but are notlimited to derivatives of the fluid of interest. For example, higherboranes are considered impurities within diborane. Disilane isconsidered an impurity in silane. Phosphine could be considered animpurity in arsine, and HF could be considered an impurity in BF₃.

The ionic liquid used in the purification process may be any of thepreviously mentioned ionic liquids. However, it should be understoodthat certain ionic liquids will be better suited to removing certainimpurities. It should also be understood that certain ionic liquids willbe better suited to working with certain fluids. In one embodiment, theionic liquid used for purification does not comprise anitrogen-containing heterocyclic cation. The fluid which may be purifiedincludes any of the previously mentioned fluids. In one embodiment, themethod is not used to purify any of the following fluids: carbondioxide, water, methane, ethane, propane, noble gases, oxygen, nitrogen,or hydrogen.

Contacting the ionic liquid with the fluid mixture may be accomplishedin any of the variety of ways. The process is selected to promoteintimate mixing of the liquid ionic compound and the fluid mixture andis conducted for a time sufficient to allow significant removal oftargeted components. Thus, systems maximizing surface area contactbetween the ionic liquid and the fluid mixture are desirable.

In one embodiment, the device is a vessel and the step of contacting thefluid mixture with the ionic liquid comprises bubbling the fluid mixturethrough the ionic liquid, as shown in FIG. 4 and previously described.In another embodiment, a scrubbing stack is used to contact the fluidmixture with the ionic liquid, with the fluid mixture and the ionicliquid flowing into the scrubbing stack. In another embodiment, thevessel containing the fluid and the ionic liquid is mechanicallyagitated in order to contact the fluid with the ionic liquid. In anotherembodiment, countercurrent flow of the ionic liquid and the fluid isused to contact the fluid with the ionic liquid in the device. Inanother embodiment, the fluid is a liquid, and the liquid and the ionicliquid are mixed to contact the fluid with the ionic liquid in thedevice.

In another aspect of the invention, a method of separating an impurityfrom a fluid mixture is provided which used a small amount of ionicliquid. The fluid mixture is contacted with the ionic liquid for thepurpose of purification only and not for uptake of the fluid by theionic liquid. Thus, a device or vessel is used to contact a small amountof ionic liquid with the fluid mixture. In this manner, a substantiallyless amount of ionic liquid could be required to obtain the purificationeffect compared to the previous illustration wherein the unstable fluidcould be taken up completely or dissolved within the ionic liquid. Aportion of the impurity is retained within the ionic liquid to produce apurified fluid.

In another aspect of the invention, a method of stabilizing an unstablefluid is provided which uses a small amount of ionic liquid. Theunstable fluid is contacted with the ionic liquid for the purpose ofstabilization only and not for uptake of the fluid by the ionic liquid.Thus, a device or vessel is used to contact a small amount of ionicliquid with the fluid. In this manner, a substantially less amount ofionic liquid could be required to obtain the stabilization effectcompared to an illustration wherein the unstable fluid could be taken upcompletely or dissolved within the ionic liquid. No decompositionproducts, or substantially less decomposition products, are produced asa result of the contact of the unstable fluid with the ionic liquid,producing a stabilized fluid.

Ionic liquids which have been dried or baked, thus leaving themsubstantially anhydrous, may exhibit greater overall capacity forremoving some gaseous components. The presence of water or otherimpurities in the ionic liquid may reduce the capacity of the ionicliquid for dissolving fluid components. In addition, the presence ofwater or other impurities may decrease the solubility of certain fluidcomponents, especially those fluid components that are hydrophobic.Dried baked ionic liquid may exhibit differential selectivities betweenvarious fluid components when compared to those ionic liquids containingmeasurable amounts of dissolved water, such as ionic liquids having beenexposed to humid atmospheres. Ionic liquids may be dried by conventionalmethods, such as by heat treatment, exposure to a reduced pressureenvironment, or a combination of heat and reduced pressure.

It is known that gas solubility in various liquids, including ionicliquids, is dependent upon temperature and pressure. Different gascomponents may each elicit a different sensitivity to temperature and/orpressure changes as pertains to the solubility of the gas component inthe ionic liquids. This differential temperature and/or temperaturedependence may be advantageously exploited by conducting variations ofthe process of the present invention at different temperatures andpressures to optimize gas component separation.

The present invention also provides a method for both storing andpurifying a fluid mixture comprising a fluid and an impurity. A vesselcontains an ionic liquid and is configured for contacting the ionicliquid with the fluid mixture. The fluid and the ionic liquid may be anyof the previously mentioned fluids and ionic liquids. The fluid iscontacted with the ionic liquid for take-up of the fluid by the ionicliquid. This may be accomplished by any of the previously decribedmethods of promoting intimate mixing of the liquid ionic compound andthe fluid mixture, or any other suitable method. A portion of theimpurities is retained within the ionic liquid to produce a purifiedfluid. The purified fluid can then be released from the device.

The present invention also provides a method of storing and stabilizingan unstable fluid. The unstable fluid may be any of the previouslymention unstable fluids, or any other fluid that tends to decompose. Theionic liquid may be any of the previously mentioned ionic liquids. Theunstable fluid is contacted with the ionic liquid for take-up of theunstable fluid by the ionic liquid. The unstable fluid may be thenstored within the ionic liquid for a period of time, during which periodof time the decomposition rate is at least reduced, and preferably thereis substantially no decomposition of the unstable fluid. In oneembodiment, the rate of decomposition is reduced by at least about 50%,more preferably at least about 75%, and most preferably at least about90%, compared with storage of the fluid under the same temperature andpressure conditions without using an ionic liquid. In the context of anunstable fluid, substantially no decomposition means that less than 10%of the molecules of the unstable fluid undergo a chemical change whilebeing stored. In one embodiment, the proportion of molecules thatundergo a decomposition reaction is preferably less than 1%, morepreferably less than 0.1%, and most preferably less than 0.01%. Althoughit is most preferable for the decomposition rate to be less than 0.01%,it should be noted that in certain applications a rate of decompositionof less than 50% over the storage period of the fluid would be useful.The period of time may range from a few minutes to several years, but ispreferably at least about 1 hour, more preferably at least about 24hours, even more preferably at least about 7 days, and most preferablyat least about 1 month.

The unstable fluid may be selected from categories such as dopants,dielectrics, etchants, thin film growth, cleaning, and othersemiconductor processes. Examples of unstable fluids include, but arenot limited to, digermane, borane, diborane, disilane, fluorine,halogenated oxy-hydrocarbons, hydrogen selenide, stibene, nitric oxide,organometallics and mixtures thereof.

The present invention also provides a method of storing and purifying afluid mixture. The storage vessel is provided with a purifying solid orliquid for contact with the fluid mixture. The purifying solid or liquidretains at least a portion of the impurity in the fluid mixture toproduce a purified fluid when the fluid is released from the storagevessel. The purifying solid or liquid may be used with any of thepreviously mentioned fluids and ionic liquids.

Various purifying materials may be used with the present invention. Thepurification or impurity removal can be used to remove impurities fromthe ionic liquid which could change the solubility of a fluid in theionic liquid. Alternatively, the purification material could remove onlyimpurities present in the incoming gas or contributed from the fluidstorage vessel that will be stored in the ionic liquid. Finally, thepurification material could have the ability to remove impurities fromboth the fluid of interest and the ionic liquid simultaneously. Thepurification materials include, but are not limited to, alumina,amorphous silica-alumina, silica (SiO₂), aluminosilicate molecularsieves, titania (TiO₂), zirconia (ZrO₂), and carbon. The materials arecommercially available in a variety of shapes of different sizes,including, but not limited to, beads, sheets, extrudates, powders,tablets, etc. The surface of the materials can be coated with a thinlayer of a particular form of the metal (e.g., a metal oxide or a metalsalt) using methods known to those skilled in the art, including, butnot limited to, incipient wetness impregnation techniques, ion exchangemethods, vapor deposition, spraying of reagent solutions,co-precipitation, physical mixing, etc. The metal can consist of alkali,alkaline earth or transition metals. Commercially available purificationmaterials includes a substrate coated with a thin layer of metal oxide(known as NHX-Plus™) for removing H₂O, CO₂ and O₂, H₂S and hydrideimpurities, such as silane, germane and siloxanes; ultra-low emission(ULE) carbon materials (known as HCX™) designed to remove tracehydrocarbons from inert gases and hydrogen; macroreticulate polymerscavengers (known as OMA™ and OMX-Plus™) for removing oxygenated species(H₂O, O₂, CO, CO₂, NO_(x), SO_(x), etc.) and non-methane hydrocarbons;and inorganic silicate materials (known as MTX™) for removing moistureand metals. All of these are available from Matheson Tri-Gas®, Newark,Calif. Further information on these purifying materials and otherpurification materials is disclosed in U.S. Pat. Nos. 4,603,148;4,604,270; 4,659,552; 4,696,953; 4,716,181; 4,867,960; 6,110,258;6,395,070; 6,461,411; 6,425,946; 6,547,861; and 6,733,734, the contentsof which are hereby incorporated by reference. Other solid purificationmaterials typically available from Aeronex, Millipore, Mykrolis, SaesGetters, Pall Corporation, Japan Pionics and used commonly in thesemiconductor gas purification applications are known in the art and areintended to be included within the scope of the present invention.

Additionally, any of the previously described storage, stabilization,and purification methods and systems may be combined to provide multipleeffects. One, two or all three methods can be independently combined toobtain a process that is best suited for the application of interest.Therefore, it is conceivable that any one method or the combination ofany of the methods could be used for different requirements andapplications. The basic steps of these combined methods will now be setforth. It will be apparent that the information previously described forthe individual methods will also be applicable for the combined methodsdescribed below. The fluids and the ionic liquids used in the combinedprocesses may be any of the previously mentioned fluids and ionicliquids.

The storage method may be combined with the method of purifying using apurifying solid. In this method, a vessel containing an ionic liquid isprovided. The fluid mixture is contacted with the ionic liquid fortake-up of the fluid by the ionic liquid. There is substantially nochemical change in the ionic liquid and the fluid. A purifying solid isprovided for contact with the fluid mixture. A portion of the impurityis retained by the purifying solid to produce a purified fluid.

The methods of storage, stabilizing, and purifying using a purifyingsolid may also be combined. A vessel containing an ionic liquid isprovided. The fluid mixture fluid is contacted with the ionic liquid fortake-up of the fluid mixture by the ionic liquid. A purifying solid isprovided for contact with the fluid mixture. A portion of the impurityis retained by the purifying solid to produce a purified fluid. Theionic liquid is stored for a period of time of at least about 1 hour,during which period of time there is substantially no degradation of theunstable fluid.

The methods of storage, stabilizing, and purifying using the ionicliquid may also be combined. A device containing an ionic liquid andconfigured for contacting the ionic liquid with the fluid mixture isprovided. The fluid mixture is introduced into the device. The fluidmixture is contacted with the ionic liquid. The fluid mixture may thenbe stored within the ionic liquid for a period of time of at least about1 hour, during which period of time there is substantially nodegradation of the unstable fluid. A portion of the impurities areretained within the ionic liquid to produce a purified unstable fluid,and the purified unstable fluid may then be released from the device.

The two purification methods may also be combined. A device containingan ionic liquid and a purifying solid therein for contact with the fluidmixture is provided. The fluid mixture is introduced into the device.The fluid mixture is contacted with the ionic liquid and with thepurifying solid. A first portion of the impurity is retained within theionic liquid and a second portion of the impurity is retained by thepurifying solid, to produce a purified fluid. The purified fluid maythen be released from the device.

The storage method may be combined with both methods of purifying. Avessel containing an ionic liquid and a purifying solid therein forcontact with the fluid mixture is provided. The fluid is contacted withthe ionic liquid for take-up of the fluid by the ionic liquid. A firstportion of the impurity is retained within the ionic liquid and a secondportion of the impurity is retained by the purifying solid, to produce apurified fluid. The purified fluid may then be released from the device.

The storage and stabilization methods may be combined with both methodsof purifying. A vessel containing an ionic liquid and a purifying solidtherein for contact with the fluid mixture is provided. The fluidmixture is introduced into the device. The fluid is contacted with theionic liquid for take-up of the fluid by the ionic liquid. The fluidmixture is stored within the ionic liquid for a period of time of atleast about 1 hour, during which period of time there is substantiallyno degradation of the unstable fluid. A first portion of the impurity isretained within the ionic liquid and a second portion of the impurity isretained by the purifying solid, to produce a purified unstable fluid.The purified fluid may then be released from the device.

The stabilization methods may be combined with both methods ofpurifying. A vessel containing an ionic liquid and a purifying solidtherein for contact with the fluid mixture is provided. The unstablefluid mixture is introduced into the device. The unstable fluid iscontacted with the ionic liquid primarily for the purposes ofstabilization and purification only, and not for the purposes of uptakeof the fluid by the ionic liquid. Thus, a device or vessel is used tocontact a small amount of ionic liquid with the fluid. In this manner, asubstantially less amount of ionic liquid could be required to obtainthe stabilization effect and the purification effect compared to theprevious illustrations wherein the unstable fluid could be taken upcompletely or dissolved within the ionic liquid. No decompositionproducts, or substantially less decomposition products, are produced asa result of the contact of the unstable fluid with the ionic liquid,producing a stabilized fluid. The fluid mixture is stored within theionic liquid for a period of time of at least about 1 hour, during whichperiod of time there is substantially no degradation of the unstablefluid. A portion of the impurity is retained within the ionic liquid toproduce a purified fluid. The purified fluid may then be released fromthe device.

EXAMPLES

For all the following Examples, a canister of ionic liquid is preparedby the following method. A stainless steel canister with a dip tube ischarged with a known quantity of the ionic liquid. The charged canisteris thermally controlled by a PID temperature controller or variac with aheating element and a thermocouple. The canister is placed on agravimetric load cell or weight scale and a pressure gauge is connectedto the canister to measure head pressure. This canister is connected toa manifold with vacuum capability and to a gas source. The canister isalso connected to an analyzer (such as FT-IR, GC, APIMS, etc.).

A vacuum bake procedure is conducted on the canister charged with theionic liquid and the manifold up to the gas cylinder, by pulling avacuum while heating. This removes any trace moisture and other volatileimpurities from the ionic liquid and the gas distribution components.The ionic liquid is allowed to cool to the desired operatingtemperature. The mass of the vacuum baked canister and ionic liquid isrecorded.

Example 1 Storage of an Unstable Gas in Ionic Liquid—B₂H₆ Stored inBMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, B₂H₆ or a gas mixture containing B₂H₆, is thenintroduced into the canister, at 5 psig, until the uptake of B₂H₆ iscomplete. The uptake can be determined gravimetrically, or by analyticalmethods. For example, the concentration or absolute amount of the B₂H₆can be measured at the inlet of the canister and the outlet of thecanister. B₂H₆ will continue to be introduced until the inlet and outletconcentrations are equivalent, indicating the BMIM[PF₆] fluid issaturated and cannot accept any further B₂H₆ under the existingconditions. At this time, the source gas flow is stopped.

The BMIM[PF₆]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored B₂H₆. The delivered gas is analyzed for B₂H₆ content. This can bedetermined gravimetrically or analytically. The total amount introducedis compared to the total amount removed to determine the loading factorof the cylinder.

Example 2 Storage of a Stable Gas in Ionic Liquid—SiF₄ Stored inBMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, SiF₄ or a gas mixture containing SiF₄, is thenintroduced into the canister, at 5 psig, until the uptake of SiF₄ iscomplete. The uptake can be determined gravimetrically, or by analyticalmethods. For example, the concentration or absolute amount of the SiF₄can be measured at the inlet of the canister and the outlet of thecanister. SiF₄ will continue to be introduced until the inlet and outletamounts are equivalent, indicating the BMIM[PF6] fluid is saturated andcannot accept any further SiF₄ under the existing conditions. At thistime, the source gas flow is stopped.

The BMIM[PF₆]-charged canister is stored for a period of time. It isthen heated, a pressure differential is applied, or it is sparged withan inert gas, in order to deliver the stored SiF₄. The delivered gas isanalyzed for SiF₄ content. This can be determined gravimetrically oranalytically. The total amount introduced is compared to the totalamount removed to determine the loading factor of the cylinder.

Example 3 Storage of an Unstable Compressed Liquefied Gas in IonicLiquid—SbH₃ Stored in MTBS

A canister of MTBS (methyl-tri-n-butylammonium methylsulfate) isprepared as described above.

The source gas, SbH₃ or a gas mixture containing SbH₃, is thenintroduced into the canister, at 5 psig, until the uptake of SbH₃ iscomplete. The uptake can be determined gravimetrically, or by analyticalmethods. For example, the concentration or absolute amount of the SbH₃can be measured at the inlet of the canister and the outlet of thecanister. SbH₃ will continue to be introduced until the inlet and outletamounts are equivalent, indicating the MTBS fluid is saturated andcannot accept any further SbH₃ under the existing conditions. At thistime, the source gas flow is stopped.

The MTBS-charged canister is then stored for a period of time. It isthen heated, a pressure differential is applied, or it is sparged withan inert gas, in order to deliver the stored SbH₃. The delivered gas isanalyzed for SbH₃ content. This can be determined gravimetrically oranalytically. The total amount introduced is compared to the totalamount removed to determine the loading factor of the cylinder.

Example 4 Storage of a Stable Compressed Liquefied Hydride Gas in IonicLiquid—PH₃ in BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, PH₃ or a gas mixture containing PH₃, is then introducedinto the canister, at 5 psig, until the uptake of PH₃ is complete. Theuptake can be determined gravimetrically, or by analytical methods. Forexample, the concentration or absolute amount of the PH₃ can be measuredat the inlet of the canister and the outlet of the canister. PH₃ willcontinue to be introduced until the inlet and outlet amounts areequivalent, indicating the BMIM[PF₆] fluid is saturated and cannotaccept any further PH₃ under the existing conditions. At this time, thesource gas flow is stopped.

The BMIM[PF₆]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored PH₃. The delivered gas is analyzed for PH₃ content. This can bedetermined gravimetrically or analytically. The total amount introducedis compared to the total amount removed to determine the loading factorof the cylinder.

Example 5 Storage of a Stable Compressed Liquefied Acid Gas in AcidicIonic Liquid—HCl in EMIM[AlCl₄]

A canister of EMIM[AlCl₄] is prepared as described above.

The source gas, HCl or a gas mixture containing HCl, is then introducedinto the canister, at the vapor pressure of HCl, until the uptake of HClis complete. The uptake can be determined gravimetrically, or byanalytical methods. For example, the concentration or absolute amount ofthe HCl can be measured at the inlet of the canister and the outlet ofthe canister. HCl will continue to be introduced until the inlet andoutlet amounts are equivalent, indicating the EMIM[AlCl₄] fluid issaturated and cannot accept any further HCl under the existingconditions. At this time, the source gas flow is stopped.

The EMIM[AlCl₄]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored HCl. The delivered gas is analyzed for HCl content. This can bedetermined gravimetrically or analytically. The total amount introducedis compared to the total amount removed to determine the loading factorof the cylinder.

Example 6 Purification of an Unstable Gas with Ionic Liquid—B₂H₆ WithBMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, B₂H₆ or a gas mixture containing B₂H₆, is then analyzedwhile by-passing the BMIM[PF₆]-charged canister, in order to determinethe concentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining BMIM[PF₆] at a pressure of 5 psig. The delivered gas from theoutlet of the canister is analyzed for impurities.

Purification of the source B₂H₆ is determined by the lack of, or adecrease in the impurities detected in the delivered gas compared to thesource gas. The capacity of the BMIM[PF₆] for impurities is calculatedby measuring the total moles of impurities removed for the moles ofBMIM[PF₆] with which the canister was charged.

Example 7 Purification of a Stable Gas with Ionic Liquid—SiF₄ withBMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, SiF₄ or a gas mixture containing SiF₄, is then analyzedwhile by-passing the BMIM[PF₆]-charged canister, in order to determinethe concentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining BMIM[PF₆] at a pressure of 5 psig. The delivered gas from theoutlet of the canister is analyzed for impurities

Purification of the source SiF₄ is determined by the lack of, or adecrease in the impurities detected in the delivered gas compared to thesource gas. The capacity of the BMIM[PF₆] for impurities is calculatedby measuring the total moles of impurities removed for the moles ofBMIM[PF₆] with which the canister was charged.

Example 8 Purification of an Unstable Compressed Liquefied Gas withIonic Liquid—SbH₃ with MTBS

A canister of MTBS is prepared as described above.

The source gas, SbH₃ or a gas mixture containing SbH₃, is then analyzedwhile by-passing the MTBS-charged canister, in order to determine theconcentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining MTBS at a pressure of 5 psig. The delivered gas from theoutlet of the canister is analyzed for impurities.

Purification of the source SbH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered gas compared to thesource gas. The capacity of the MTBS for impurities is calculated bymeasuring the total moles of impurities removed for the moles of MTBSwith which the canister was charged.

Example 9 Purification of an Unstable Compressed Liquefied Gas in theLiquid Phase with Ionic Liquid—SbH₃ with MTBS

A canister of MTBS is prepared as described above.

The liquid phase source material, SbH₃, is flowed through the apparatus,by-passing the MTBS-charged canister, vaporized, and analyzed in orderto determine the concentration of impurities. Once the impurity levelsin the source fluid have been established, liquid phase source materialis flowed into the canister containing MTBS, at the vapor pressure ofSbH₃. The delivered liquid from the outlet of the canister is vaporizedand analyzed to determine the concentration of the impurities.

Purification of the source SbH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered liquid whencompared to the source liquid, as determined by analysis in the vaporphase. The capacity of the MTBS for impurities is calculated bymeasuring the total moles of impurities removed for the moles of MTBSwith which the canister was charged.

Example 10 Purification of a Stable Compressed Liquefied Hydride Gaswith Ionic Liquid—PH₃ with BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, PH₃ or a gas mixture containing PH₃, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining BMIM[PF₆] at the vapor pressure of PH₃. The delivered gasfrom the outlet of the canister is analyzed for impurities.

Purification of the stored PH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered gas compared to thesource gas. The capacity of the BMIM[PF₆] for impurities is calculatedby measuring the total moles of impurities removed for the moles ofBMIM[PF₆] with which the canister was charged.

Example 11 Purification of a Stable Compressed Liquefied Acid Gas withIonic Liquid—HCl with EMIM[AlCl₄]

A canister of EMIM[AlCl₄]is prepared as described above.

The source gas, HCl or a gas mixture containing HCl, is analyzed whileby-passing the EMIM[AlCl₄]-charged canister, in order to determine theconcentration of moisture. Once the H₂O concentration in the source gashave been established, source gas is flowed into the canister containingEMIM[AlCl₄] at a pressure of 5 psig. The gas is bubbled through theEMIM[AlCl₄] inside the canister and the delivered gas at the outlet ofthe canister is analyzed to measure the moisture content.

Purification of the stored HCl is determined by the lack of, or adecrease in the H₂O impurity concentration detected in the delivered gascompared to the source gas. The capacity of the EMIM[AlCl₄] forimpurities is calculated by measuring the total moles of H₂O removed forthe moles of EMIM[AlCl₄]with which the canister was charged.

Example 12 Purification of a Stable Compressed Liquefied Gas in theLiquid Phase with Ionic Liquid—NH₃ with EMIM[Acetat]

A canister of EMIM[Acetat] is prepared as described above.

The liquid phase source material, NH₃, is flowed through the apparatus,by-passing the EMIM[Acetat]-charged canister, vaporized, and analyzed inorder to determine the concentration of impurities. Once the impuritylevels in the source fluid have been established, liquid phase sourcematerial is flowed into the canister containing EMIM[Acetat], at thevapor pressure of NH₃. The delivered liquid from the outlet of thecanister is vaporized and analyzed to determine the concentration of theimpurities.

Purification of the source NH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered liquid whencompared to the source liquid, as determined by analysis in the vaporphase. The capacity of the EMIM[Acetat] for impurities is calculated bymeasuring the total moles of impurities removed for the moles ofEMIM[Acetat] with which the canister was charged.

Example 13 Stabilization of an Unstable Gas with Ionic Liquid—B₂H₆ withBMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, B₂H₆ or a gas mixture containing B₂H₆, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of B₂H₆ and decomposition products. Once theseconcentrations in the source gas have been established, source gas isflowed into the canister containing BMIM[PF₆] until it has equilibratedto a pressure of 5 psig. At this time, the flow of the source materialis stopped.

With the source gas flow off, the gas from the outlet of the canistercontaining the BMIM[PF₆] is then analyzed for B₂H₆ and decompositionproducts.

Stabilization of the source B₂H₆ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery ofB₂H₆.

Example 14 Stabilization of an Unstable Compressed Liquefied Gas in theLiquid Phase with Ionic Liquid—SbH₃ with MTBS

A canister of MTBS is prepared as described above.

The liquid phase source material, SbH₃, is flowed through the apparatus,by-passing the MTBS-charged canister, vaporized, and analyzed in orderto determine the concentration of decomposition products. Once thedecomposition levels in the source fluid have been established, liquidphase source material is flowed into the canister containing MTBS, atthe vapor pressure of SbH₃. At this time, the flow of the sourcematerial is stopped.

With the source flow off, the delivered liquid from the outlet of thecanister is vaporized and analyzed for SbH₃ and decomposition products.

Stabilization of the source SbH₃ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery ofSbH₃.

Example 15 Storage and Purification of an Unstable Gas in IonicLiquid—B₂H₆ With BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, B₂H₆ or a gas mixture containing B₂H₆, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining BMIM[PF₆] at a pressure of 5 psig, until the uptake of B₂H₆is complete. The uptake can be determined gravimetrically, or byanalytical methods. For example, the concentration or absolute amount ofthe B₂H₆ can be measured at the inlet of the canister and the outlet ofthe canister. B₂H₆ will continue to be introduced until the inlet andoutlet concentrations are equivalent, indicating the BMIM[PF₆] fluid issaturated and cannot accept any further B₂H₆ under the existingconditions. At this time, the source gas flow is stopped.

The BMIM[PF₆]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored B₂H₆. The delivered gas from the outlet of the canister isanalyzed for impurities.

The canister is then stored for a period of time. Samples of B₂H₆ aretaken at time intervals in order to determined the stability of the B₂H₆in the BMIM[PF₆]. Purification of the source B₂H₆ is determined by thelack of, or a decrease in the impurities detected in the delivered gasfrom the canister compared to the source gas. The capacity of theBMIM[PF₆] for impurities is calculated by measuring the total moles ofimpurities removed for the moles of BMIM[PF6] with which the canisterwas charged.

Example 16 Storage and Purification of a Stable Gas in Ionic Liquid—SiF₄with BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, SiF₄ or a gas mixture containing SiF₄, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining BMIM[PF₆] at a pressure of 5 psig, until the uptake of SiF₄is complete. The uptake can be determined gravimetrically, or byanalytical methods. For example, the concentration or absolute amount ofthe SiF₄ can be measured at the inlet of the canister and the outlet ofthe canister. SiF₄ will continue to be introduced until the inlet andoutlet concentrations are equivalent, indicating the BMIM[PF₆] fluid issaturated and cannot accept any further SiF₄ under the existingconditions. At this time, the source gas flow is stopped.

The BMIM[PF₆]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored SiF₄. The delivered gas from the outlet of the canister isanalyzed for impurities.

Purification of the source SiF₄ is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the BMIM[PF₆] forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of BMIM[PF₆] with which the canister was charged.

Example 17 Storage and Purification of an Unstable Compressed LiquefiedGas in Ionic Liquid—SbH₃ with MTBS

A canister of MTBS is prepared as described above.

The source gas, SbH₃ or a gas mixture containing SbH₃, is analyzed whileby-passing the MTBS-charged canister, in order to determine theconcentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining MTBS at a pressure of 5 psig, until the uptake of SbH₃ iscomplete. The uptake can be determined gravimetrically, or by analyticalmethods. For example, the concentration or absolute amount of the SbH₃can be measured at the inlet of the canister and the outlet of thecanister. SbH₃ will continue to be introduced until the inlet and outletconcentrations are equivalent, indicating the MTBS fluid is saturatedand cannot accept any further SbH₃ under the existing conditions. Atthis time, the source gas flow is stopped.

The MTBS-charged canister is then heated, a pressure differential isapplied, or it is sparged with an inert gas, in order to deliver thestored SbH₃. The delivered gas from the outlet of the canister isanalyzed for impurities.

Purification of the source SbH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the MTBS forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of MTBS with which the canister was charged.

Example 18 Storage and Purification of a Stable Compressed Liquefied Gasin Ionic Liquid—PH₃ with BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, PH₃ or a gas mixture containing PH₃, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining BMIM[PF₆] at a pressure of 5 psig, until the uptake of PH₃ iscomplete. The uptake can be determined gravimetrically, or by analyticalmethods. For example, the concentration or absolute amount of the PH₃can be measured at the inlet of the canister and the outlet of thecanister. PH₃ will continue to be introduced until the inlet and outletconcentrations are equivalent, indicating the BMIM[PF₆] liquid issaturated and cannot accept any further PH₃ under the existingconditions. At this time, the source gas flow is stopped.

The BMIM[PF₆]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored PH₃. The delivered gas from the outlet of the canister isanalyzed for impurities.

Purification of the source PH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the BMIM[PF₆] forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of BMIM[PF₆] with which the canister was charged.

Example 19 Storage and Purification of a Stable Compressed Liquefied Gasin Acidic Ionic Liquid—HCl with EMIM[AlCl₄]

A canister of EMIM[AlCl₄] is prepared as described above.

The source gas, HCl or a gas mixture containing HCl, is analyzed whileby-passing the EMIM[AlCl₄]-charged canister, in order to determine theconcentration of impurities. Once the impurity concentrations in thesource gas have been established, source gas is flowed into the canistercontaining EMIM[AlCl₄] at a pressure of 5 psig, until the uptake of HClis complete. The uptake can be determined gravimetrically, or byanalytical methods. For example, the concentration or absolute amount ofthe HCl can be measured at the inlet of the canister and the outlet ofthe canister. HCl will continue to be introduced until the inlet andoutlet concentrations are equivalent, indicating the EMIM[AlCl₄] liquidis saturated and cannot accept any further HCl under the existingconditions. At this time, the source gas flow is stopped.

The EMIM[AlCl₄]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored HCl. The delivered gas from the outlet of the canister isanalyzed for impurities.

Purification of the source HCl is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the EMIM[AlCl₄] forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of EMIM[AlCl₄] with which the canister wascharged.

Example 20 Storage and Stabilization of an Unstable Gas in IonicLiquid—B₂H₆ With BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, B₂H₆ or a gas mixture containing B₂H₆, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of B₂H₆ and decomposition products. Once theseconcentrations in the source gas have been established, source gas isflowed into the canister containing BMIM[PF₆] at a pressure of 5 psig,until the uptake of B₂H₆ is complete. The uptake can be determinedgravimetrically, or by analytical methods. For example, theconcentration or absolute amount of the B₂H₆ can be measured at theinlet of the canister and the outlet of the canister. B₂H₆ will continueto be introduced until the inlet and outlet concentrations areequivalent, indicating the BMIM[PF₆] fluid is saturated and cannotaccept any further B₂H₆ under the existing conditions. At this time, thesource gas flow is stopped.

The BMIM[PF₆]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored B₂H₆. The delivered gas from the outlet of the canister isanalyzed for B₂H₆ and decomposition products.

Stabilization of the source B₂H₆ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery to thesource material.

Example 21 Storage and Stabilization of an Unstable Compressed LiquefiedGas With Ionic Liquid—SbH₃ With MTBS

A canister of MTBS is prepared as described above.

The source gas, SbH₃ or a gas mixture containing SbH₃, is analyzed whileby-passing the MTBS-charged canister, in order to determine theconcentration of SbH₃ and decomposition products. Once theseconcentrations in the source gas have been established, source gas isflowed into the canister containing MTBS at a pressure of 5 psig, untilthe uptake of SbH₃ is complete. The uptake can be determinedgravimetrically, or by analytical methods. For example, theconcentration or absolute amount of the SbH₃ can be measured at theinlet of the canister and the outlet of the canister. SbH₃ will continueto be introduced until the inlet and outlet concentrations areequivalent, indicating the MTBS fluid is saturated and cannot accept anyfurther SbH₃ under the existing conditions. At this time, the source gasflow is stopped.

The MTBS-charged canister is then heated, a pressure differential isapplied, or it is sparged with an inert gas, in order to deliver thestored SbH₃. The delivered gas from the outlet of the canister isanalyzed for SbH₃ and decomposition products.

Stabilization of the source SbH₃ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery ofSbH₃.

Example 22 Stabilization and Purification of an Unstable Gas with IonicLiquid—B₂H₆ with BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, B₂H₆ or a gas mixture containing B₂H₆, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of B₂H₆, impurities, and decomposition products. Oncethese concentrations in the source gas have been established, source gasis flowed into the canister containing BMIM[PF₆] until it hasequilibrated at a pressure of 5 psig. At this time, the source gas flowis stopped.

With the source gas flow off, the gas from the outlet of the canistercontaining the BMIM[PF₆] is then analyzed for B₂H₆, impurities, anddecomposition products.

Stabilization of the source B₂H₆ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery ofB₂H₆.

Purification of the source B₂H₆ is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the BMIM[PF₆] forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of BMIM[PF₆] with which the canister was charged.

Example 23 Stabilization and Purification of an Unstable CompressedLiquefied Gas With Ionic Liquid—SbH3 With MTBS

A canister of MTBS is prepared as described above.

The source gas, SbH₃ or a gas mixture containing SbH₃, is analyzed whileby-passing the MTBS-charged canister, in order to determine theconcentration of SbH₃, impurities, and decomposition products. Oncethese concentrations in the source gas have been established, source gasis flowed into the canister containing MTBS until it has equilibrated at5 psig. At this time, the source gas flow is stopped.

With the source gas flow off, the gas from the outlet of the canistercontaining the MTBS is then analyzed for SbH₃, impurities, anddecomposition products.

The MTBS-charged canister is then heated, a pressure differential isapplied, or it is sparged with an inert gas, in order to deliver thestored SbH₃. The delivered gas from the outlet of the canister isanalyzed for SbH₃, impurities, and decomposition products.

Stabilization of the source SbH₃ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery ofSbH₃.

Purification of the source SbH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the MTBS forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of MTBS with which the canister was charged.

Example 24 Storage, Purification, and Stabilization of an Unstable Gaswith Ionic Liquid—B₂H₆ with BMIM[PF₆]

A canister of BMIM[PF₆] is prepared as described above.

The source gas, B₂H₆ or a gas mixture containing B₂H₆, is analyzed whileby-passing the BMIM[PF₆]-charged canister, in order to determine theconcentration of B₂H₆, impurities, and decomposition products. Oncethese concentrations in the source gas have been established, source gasis flowed into the canister containing BMIM[PF₆] at a pressure of 5psig, until the uptake of B₂H₆ is complete. The uptake can be determinedgravimetrically, or by analytical methods. For example, theconcentration or absolute amount of the B₂H₆ can be measured at theinlet of the canister and the outlet of the canister. B₂H₆ will continueto be introduced until the inlet and outlet concentrations areequivalent, indicating the BMIM[PF₆] fluid is saturated and cannotaccept any further B₂H₆ under the existing conditions. At this time, thesource gas flow is stopped.

The BMIM[PF₆]-charged canister is then heated, a pressure differentialis applied, or it is sparged with an inert gas, in order to deliver thestored B₂H₆. The delivered gas from the outlet of the canister isanalyzed for B₂H₆, impurities, and decomposition products.

Stabilization of the source B₂H₆ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery ofB₂H₆.

Purification of the source B₂H₆ is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the BMIM[PF₆] forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of BMIM[PF₆] with which the canister was charged.

Example 25 Storage, Purification, and Stabilization of an UnstableCompressed Liquefied Gas With Ionic Liquid—SbH₃ With MTBS

A canister of MTBS is prepared as described above.

The source gas, SbH₃ or a gas mixture containing SbH₃, is analyzed whileby-passing the MTBS-charged canister, in order to determine theconcentration of SbH₃, impurities, and decomposition products. Oncethese concentrations in the source gas have been established, source gasis flowed into the canister containing MTBS at a pressure of 5 psig,until the uptake of SbH₃ is complete. The uptake can be determinedgravimetrically, or by analytical methods. For example, theconcentration or absolute amount of the SbH₃ can be measured at theinlet of the canister and the outlet of the canister. SbH₃ will continueto be introduced until the inlet and outlet concentrations areequivalent, indicating the MTBS fluid is saturated and cannot accept anyfurther SbH₃ under the existing conditions. At this time, the source gasflow is stopped.

The MTBS-charged canister is then heated, a pressure differential isapplied, or it is sparged with an inert gas, in order to deliver thestored SbH₃. The delivered gas from the outlet of the canister isanalyzed for SbH₃, impurities, and decomposition products.

Stabilization of the source SbH₃ is determined by the lack of, or adecrease in the decomposition products detected in the delivered gascompared to the source gas, in addition to quantitative recovery ofSbH3.

Purification of the source SbH₃ is determined by the lack of, or adecrease in the impurities detected in the delivered gas from thecanister compared to the source gas. The capacity of the MTBS forimpurities is calculated by measuring the total moles of impuritiesremoved for the moles of MTBS with which the canister was charged.

The embodiments described above and shown herein are illustrative andnot restrictive. The scope of the invention is indicated by the claimsrather than by the foregoing description and attached drawings. Theinvention may be embodied in other specific forms without departing fromthe spirit of the invention. Accordingly, these and any other changeswhich come within the scope of the claims are intended to be embracedtherein.

1. A fluid storage and dispensing system, comprising: a fluid storage and dispensing vessel configured to selectively dispense a fluid therefrom; and an ionic liquid that is not substantially chemically reactive with the fluid, the ionic liquid disposed in the vessel, wherein the ionic liquid is selected from the group consisting of pyridinium salts, pyrrolidinium salts, phosphonium salts, ammonium salts, tetralkylammonium salts, guanidinium salts, uronium salts, and compounds comprising: a cation component selected from the group consisting of mono-substituted imidazoliums, di-substituted imidazoliums, and tri-substituted imidazoliums, and an anion component selected from the group consisting of acetate, cyanates, decanoates, halogenides, sulfates, sulfonates, amides, imides, methanes, antimonates, tetrachoroaluminate, thiocyanate, tosylate, carboxylate, cobalt-tetracarbonyl, trifluoroacetate and tris(trifluoromethylsulfonyl)methide; and mixtures thereof; wherein the ionic liquid reversibly takes up the fluid when contacted therewith, and from which the fluid is releasable under dispensing conditions.
 2. The fluid storage and dispensing system of claim 1 wherein the ionic liquid comprises a cation component selected from the group consisting of pyridiniums, pyrrolidinium salts, phosphoniums, ammoniums, tetralkylammoniums, guanidiniums, and uroniums; and an anion component selected from the group consisting of acetate, cyanates, decanoates, halogenides, sulfates, sulfonates, amides, imides, methanes, borates, phosphates, antimonates, tetrachoroaluminate, thiocyanate, tosylate, carboxylate, cobalt-tetracarbonyl, trifluoroacetate and tris(trifluoromethylsulfonyl)methide.
 3. The fluid storage and dispensing system of claim 1 wherein the fluid storage and dispensing vessel is configured to bubble the fluid mixture through the ionic liquid.
 4. The fluid storage and dispensing system of claim 1 wherein the fluid storage and dispensing vessel is configured to mechanically agitate the fluid and the ionic liquid. 